The invention relates to a method for complementing dynamic resource-level path computation with a resource grouping constraint in a network and in particular in a wavelength division multiplexing (WDM) network.
A network can be modelled as a collection of switches or other network elements which are interconnected to each other via links. Each link can further be populated with a pool of resources. In the context of wavelength division layer networks these resources can refer to fixed or tunable wavelength channels available for a WDM layer connection.
In general, there exist relationships between the resources of a network. For example, attributes of a resource or operations on a resource within the network may have an effect on other resources of the network. These relationships between the resources may be induced by hardware or device limitations, operational dependencies or non-orthogonalities. There are also situations where an entire set of resources has to be treated in a manner distinct from other resources due to the nature of specific algorithm implementations which process the resource information base of the network in a particular manner. Relationships between resources in a network can also be induced directly through application requirements of specific operational policies defined for the respective network.
If relationships between resources are not known to an application which is provided to perform a computation on the resource information base this application may be unable to produce correct results, and/or be forced to execute heuristic-based procedures which achieve only sub-optimal results. Such heuristic-based procedures can often devolve into exhaustive searches which are unacceptable, for example in an on-line or time-critical environment.
Resource information models currently used for traffic engineering purposes treat provisionable resources of a network as entirely individual and unrelated entities. For example, the WSON architecture as defined within IETF identifies the notion of asymmetries within a switching element but does not make any provisions for the notion that the resources affected by these asymmetries may be inter-related in some non-trivial manner. This lack of relationship information data renders current applications unable to generate computationally complete results under certain conditions.
At present common information models treat resources as entirely individual entities, hence, any relationships amongst them are not expressed through the information model. Applications making use of this information model of the network are therefore currently not able to compute complete solutions in all cases, and thus are forced to utilize more heuristic approaches.
Consequently, there is a need to provide a method for complementing dynamic resource-level path computation taking into account relationships between resources.